Intake manifolds commonly deliver air to the cylinders of an engine. Other fluids are typically delivered to the cylinders of an engine by systems connected to or separate from the intake manifold, such as fuel injection systems, exhaust gas recirculation systems, positive crankcase ventilation systems and fuel tank vapor systems. The components for these various systems are commonly assembled separately from the intake manifold and individually mounted on the engine or manifold.
Separate assembly of the intake manifold and the various fluid delivery system components can entail considerable difficulty and expense due to the interdependency of the various systems. Proper alignment, tight connections and fully coordinated control systems are often critical to the optimum functioning of the various systems. Such design and manufacturing requirements can be difficult to meet when separately assembling the various system assemblies and mounting them on an engine. For similar reasons, mounting the assembled components of these various systems as separate assemblies can also require substantial effort and expense.
The fluid delivery systems described above typically include many relatively small and fragile components as compared to other engine components such as blocks and cylinder heads. Some of the components of the fluid delivery systems must be connected with similar components in other fluid delivery systems after their attachment to the engine. Engine assembly can therefore be made very complex due to the methods required to connect the components of the various fluid delivery systems to one another and to the engine as contrasted with the methods used to assemble the larger engine components.
Many of the fluid delivery system assemblies are often rigidly attached to the engine in close proximity to one another and have a number of rigid connections between the various components of the different systems. Therefore, access to one system assembly often requires the difficult disengagement of a number of rigid connections as well as removal of a number of components to gain access to the desired components.